Arrange `Ce^(3+),La^(3+), Pm^(3)` and `Yb^(3+)` in increasing order of their size -

Options

A. `Yb^(3+) lt PM^(3+) lt Ce^(3+) lt La^(3+)`
B. `Ce^(3+) lt Yb^(3+) lt Pm^(3+) lt La^(3+)`
C. `Yb^(3+) lt Pm^(3+) lt La^(3+) lt Ce^(3+)`
D. `Pm^(3+) lt La^(3+) lt Ce^(3+) lt Yb^(3+)`

Answer

A

Explanation

On account of lanthanide contraction, ionic size decreases from `La^(3+)` to `Lu^(3+)`